The present invention relates to a photographic printing method.
In conventional photographic printing methods, an original film from which prints are made is passed through a printing gate of a printer once. Specifically, image frames of the original film are placed in the printing gate in order and measured to detect image information of the respective images. Based on the detected image information of each image frame, the photographic printer calculates a proper exposure and makes a print according to the calculated exposure. In such printing methods, because the measurement and the printing are alternatively effected, printing operation is inefficient, laborious, tedious and probably expensive.
To achieve a high rate of efficiency in printing operation proposed in, for example, Japanese Patent Unexamined Publication No. 61-91,648 is a printing method in which an original film is forwarded, frame by frame, to measure the respective image frames so as to detect image information thereof and thereafter, the original film is reversed to make prints frame by frame and printed by automatic exposure control according to the detected image information of the respective images. For printing in the method taught by the above Publication, a notch sensor is provided in the photographic printer to detect notches formed in one side margin of the negative film, one for each frame, so as TO automatically place each frame correctly in a printing station. The notch is formed on a transversal center line of each frame to be printed. However, the notch may mistakenly be formed at a short distance from the center line. Since a frame whose notch is away from the center line is placed in incorrect printing position an incomplete image is projected on a photographic paper. Upon measuring a frame image to detect image information necessary for printing a blank space between frames is partially scanned by a scanner. Therefore, accurate image information cannot be recorded.
In the case of a negative film having no notches, it is necessary to advance the negative film either by a predetermined constant length so as to place each frame at a correct position in the printing station or by detecting a border between a frame and a blank space adjacent to the frame by means of a scanner so as to place the detected border at a predetermined position. However, because blank spaces between frames are not always equally dimensioned or because the border between a frame and a blank space adjacent to the frame is not always sharp for some images, in particular images of scenes including an artificially lightened object at a center thereof, it is often hard to automatically place the respective frame in a correct position.